Matthew has OCD. Not that he knows that's what it is. He just likes things clean, he really hates germs, or going outside, and he feels safest upstairs in his room and the front bedroom, where he can control the dirt, and where he can watch everything that's going on outside, making notes on his neighbours' activities. When a little boy, Teddy, from next door goes missing one day, it turns out that Matthew was the last person to see him, and with all of his neighbours as suspects Matthew struggles against his crippling anxieties in order to try and uncover the truth of what happened to Teddy.